package environment

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"github.com/docker/docker/api/types"
	"github.com/docker/docker/client"
	"github.com/pkg/errors"
	"golang.org/x/net/context"
)

// Execution contains information about the current test execution and daemon
// under test
type Execution struct {
	client            client.APIClient
	DaemonInfo        types.Info
	PlatformDefaults  PlatformDefaults
	protectedElements protectedElements
}

// PlatformDefaults are defaults values for the platform of the daemon under test
type PlatformDefaults struct {
	BaseImage            string
	VolumesConfigPath    string
	ContainerStoragePath string
}

// New creates a new Execution struct
func New() (*Execution, error) {
	client, err := client.NewEnvClient()
	if err != nil {
		return nil, errors.Wrapf(err, "failed to create client")
	}

	info, err := client.Info(context.Background())
	if err != nil {
		return nil, errors.Wrapf(err, "failed to get info from daemon")
	}

	return &Execution{
		client:            client,
		DaemonInfo:        info,
		PlatformDefaults:  getPlatformDefaults(info),
		protectedElements: newProtectedElements(),
	}, nil
}

func getPlatformDefaults(info types.Info) PlatformDefaults {
	volumesPath := filepath.Join(info.DockerRootDir, "volumes")
	containersPath := filepath.Join(info.DockerRootDir, "containers")

	switch info.OSType {
	case "linux":
		return PlatformDefaults{
			BaseImage:            "scratch",
			VolumesConfigPath:    toSlash(volumesPath),
			ContainerStoragePath: toSlash(containersPath),
		}
	case "windows":
		baseImage := "microsoft/windowsservercore"
		if override := os.Getenv("WINDOWS_BASE_IMAGE"); override != "" {
			baseImage = override
			fmt.Println("INFO: Windows Base image is ", baseImage)
		}
		return PlatformDefaults{
			BaseImage:            baseImage,
			VolumesConfigPath:    filepath.FromSlash(volumesPath),
			ContainerStoragePath: filepath.FromSlash(containersPath),
		}
	default:
		panic(fmt.Sprintf("unknown info.OSType for daemon: %s", info.OSType))
	}
}

// Make sure in context of daemon, not the local platform. Note we can't
// use filepath.FromSlash or ToSlash here as they are a no-op on Unix.
func toSlash(path string) string {
	return strings.Replace(path, `\`, `/`, -1)
}

// IsLocalDaemon is true if the daemon under test is on the same
// host as the CLI.
//
// Deterministically working out the environment in which CI is running
// to evaluate whether the daemon is local or remote is not possible through
// a build tag.
//
// For example Windows to Linux CI under Jenkins tests the 64-bit
// Windows binary build with the daemon build tag, but calls a remote
// Linux daemon.
//
// We can't just say if Windows then assume the daemon is local as at
// some point, we will be testing the Windows CLI against a Windows daemon.
//
// Similarly, it will be perfectly valid to also run CLI tests from
// a Linux CLI (built with the daemon tag) against a Windows daemon.
func (e *Execution) IsLocalDaemon() bool {
	return os.Getenv("DOCKER_REMOTE_DAEMON") == ""
}

// Print the execution details to stdout
// TODO: print everything
func (e *Execution) Print() {
	if e.IsLocalDaemon() {
		fmt.Println("INFO: Testing against a local daemon")
	} else {
		fmt.Println("INFO: Testing against a remote daemon")
	}
}

// APIClient returns an APIClient connected to the daemon under test
func (e *Execution) APIClient() client.APIClient {
	return e.client
}
